LIN bus network, integrated circuit and method of communicating thereon

ABSTRACT

A LIN network comprises a transmit driver and a receive comparator for communicating low frequency signals on a single communication bus. The transmit driver is operably coupled to a high frequency detector to detect a high frequency component on the low frequency signal. In response to detecting the high frequency component the LIN network is arranged to perform one or both of the following: route the low frequency signal having a high frequency component through a low pass filter; and/or bypass the low frequency signal having a high frequency component from passing through an active device operably coupled between the transmit driver and the single communication bus.

FIELD OF THE INVENTION

One embodiment of the present invention relates to a single-wire serialcommunication protocol based on the common serial communicationinterface (SCI). The invention is applicable to, but not limited to, amechanism and method to improve electro magnetic susceptibility in alinear Interconnect Network (LIN).

BACKGROUND OF THE INVENTION

Linear Interconnect Networking (LIN) is an industry standard for asingle-wire serial communication protocol, based on the common serialcommunication interface (SCI) (UART) byte-word interface. UARTinterfaces are now available as a low cost silicon module and areprovided as a feature on the majority of micro-controllers. UARTinterfaces can take many forms, for example they can be implemented insoftware or as a state machine interface for application specificintegrated circuits (ASICs).

LIN is targeted as an easy to use, open, communication standard,designed to provide more reliable vehicle diagnostics. Access to thecommunication medium in a LIN network is controlled by a master node, sothat no arbitration or collision management software or control isrequired in the slave nodes, thus providing a guarantee of worst-caselatency times for signal transmission.

A node in a LIN network does not make use of any information about thesystem configuration, except for the denomination of the master node.Nodes can be added to the LIN network without requiring hardware orsoftware changes in other slave nodes. The size of a LIN network istypically under twelve nodes, although the LIN network is not generallyrestricted to twelve nodes. This results from a use of only ‘64’identifiers together with a relatively low transmission speed of 20Kbits/sec. The clock synchronization, the simplicity of UARTcommunication, and the single-wire medium are often cited as majorfactors for the cost efficiency of LIN.

Referring now to FIG. 1, a simplified LIN node 100 is illustrated. FIG.1 shows the basic block diagram of the LIN physical layer. A digitalinput, referred to as txd 105, drives the transmit (Tx) LIN bus driver110. When the digital input txd 105 is at high logic level, the LINoutput, on the single communication line LIN communication bus 115, isat a high level, i.e. the supply voltage of the vehicle battery referredto as V_(bat).

The signal voltage swing on the single communication LIN bus swings fromV_(bat) to a low level of approximately 1V. The Tx LIN bus driver 110 issupplied by V_(bat). Each receiver element in a LIN network comprises acomparator 120, which detects when the voltage signal on the singlecommunication LIN bus crosses a value of 50% of V_(bat). The voltagelevel of the comparator output is therefore controlled by the referencesignal 125 input to the comparator 120. When the voltage on the singlecommunication LIN bus is high, i.e. over a level of 50% of V_(bat), thereceiver logic (rxd) output 130 is at a high (V_(bat)) logic level.

Referring now to FIG. 2, A LIN network 200 is illustrated. The LINnetwork 200 comprises one master node (control unit) 205 and one or moreslave nodes 220, 230. All nodes include a slave communication task 215,225, 235 that is divided between a transmit task and a receive task. Themaster node 205 also includes a transmit task 210 and a receive slavetask 215. Communication in an active LIN network is performed on the LINbus 240 and is always initiated by a master task 210.

Referring now to FIG. 3, the simplified circuit of a node isillustrated. FIG. 3 illustrates the output stage of the Tx bus driver110. The output stage is connected to V_(bat) 305 through a diode 310. Aresistive load 315 is used as a pull-up function for the output stage,i.e. the single LIN communication bus 115. A typical value for aresistive load 315 of a slave device is 30 Kohm. Thus, the 30 Kohmspull-up resistor is present in each internal LIN node. However, todistinguish the Master node from a slave node a 1 KOhms resistor isplaced in series with another diode, and is located outside of theintegrated circuit. The transistor 320 functions as a switch, throughcontrol of the serial communication interface (SCI) 330, and istherefore able to pull-down the single communication LIN bus 115 to alow level.

However, it has been recognised that when Electro Magnetic Interference(EMI) occurs on the single communication LIN bus 115, via introductionof high frequency component interference, say from a circuit or deviceoperational in the vehicle, the LIN network may fail the Direct PowerInjection (DPI) test. In particular, there exists a need to sustain 36dBm in DPI test (+/−40V on single communication LIN bus 115) with a lowtransition time between the communication signal transitioning betweenhigh and low voltage levels.

Thus, a need exists for an improved LIN network, integrated circuit andmethod of operation therefor.

SUMMARY OF THE INVENTION

In accordance with aspects of the present invention, there is provided aLIN network, an integrated circuit and method of operation therefor, asdefined in the appended Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a known simplified circuit diagram of a LIN node.

FIG. 2 illustrates an overview of a known LIN network.

FIG. 3 illustrates a known transmit driver circuit employed in a LINnetwork.

Exemplary embodiments of the present invention will now be described, byway of example only, with reference to the accompanying drawings, inwhich:

FIG. 4 illustrates a circuit diagram of a LIN network adapted inaccordance with one embodiment of the present invention;

FIG. 5 illustrates a high frequency detector of a LIN network inaccordance with one embodiment of the present invention;

FIG. 6 illustrates a test circuit used to validate a performanceimprovement of embodiments of the present invention;

FIG. 7 illustrates a known waveform of a signal on a LIN network that isaffected by a high frequency component;

FIG. 8 illustrates an improved waveform of a signal on a LIN networkwhen employing embodiments of the present invention; and

FIG. 9 illustrates a method of operation of a LIN network in accordancewith embodiments of the present invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In one embodiment of the present invention, a LIN network is describedthat comprises a transmit driver and a receive comparator forcommunicating on a single communication bus. The transmit driver isoperably coupled to a high frequency detector to detect a high frequencycomponent on a low frequency signal. In response to detecting the highfrequency component, the LIN network is arranged to perform one or bothof the following: route the low frequency signal having a high frequencycomponent through a low pass filter; and/or bypass the low frequencysignal having a high frequency component from passing through an activedevice operably coupled between the transmit driver and the singlecommunication bus.

In this manner, the provision of a bypass circuit around the activedevice, which is activated when a high frequency component is detected,removes a rectification effect on the low frequency signal due to thehigh frequency component when passed through the active device.Furthermore, the routeing of the low frequency signal having a highfrequency component through a low-pass filter, when a high frequencycomponent is detected, is designed to minimise any adverse effect ondetermining an accurate signal transition between a high and low voltagelevel due to the high frequency component.

In one embodiment of the present invention, the low frequency signal isa LIN signal and an average of the LIN signal is routed through the lowpass filter to minimise any dc offset caused by the HF component.

In one embodiment of the present invention, the active device is adiode.

In one embodiment of the present invention, the transmit driver isoperably coupled to a supply voltage, for example a battery voltage of avehicle, and is configured to operate in one of at least two modesutilising one of at least two loops.

In one embodiment of the present invention, one of the at least twoloops is a high frequency mode loop that is selected in response todetecting the high frequency component on the low frequency signal.

In one embodiment of the present invention, the high frequency mode loopincorporates the low pass filter when the high frequency component isdetected.

In one embodiment of the present invention, the LIN network comprises afirst switch (S1) arranged in parallel to the active device and operablycoupled to the HF detector such that the first switch (S1) is switchedto a closed position in a HF loop to bypass the active device when thehigh frequency component is detected.

In one embodiment of the present invention, the operation of both thefirst switch and the active device may be provided by a single PMOSFET,thereby simplifying the circuit.

In one embodiment of the present invention, a method of communicating ona LIN network comprising a transmit driver operably coupled to a singlecommunication bus via an active device is described. The methodcomprises communicating a low frequency signal having a high frequencycomponent on a single communication bus and detecting the high frequencycomponent on the low frequency signal. In response to detecting the highfrequency component, one or both of the following is/are performed: (i)routeing the low frequency signal having a high frequency componentthrough a low pass filter; and/or (ii) bypassing the low frequencysignal having a high frequency component signal from passing through theactive device.

One embodiment of the present invention will be described in terms of aLIN network for in-vehicle communication. However, it will beappreciated by a skilled artisan that the inventive concept hereindescribed may be embodied in any type of single-wire communicationsystem.

In one embodiment of the present invention, the aforementioned problemsare resolved by detecting a high frequency (HF) condition/mode on a LINnetwork. Although the invention is described with reference to a singlecommunication line LIN communication bus 115, it is envisaged that theinventive concept is equally applicable to any single communication linesystem. Thus, hereinafter the term ‘LIN bus’ should be interpreted asmeaning any single line communication bus.

In one embodiment of the present invention, the term ‘high frequency’ isarranged to be an order higher than a typical low frequency LIN signal.In one embodiment, the high frequency component may be in the range of 1MHz to 1 GHz. Thereafter, when operating in a ‘HF mode’, i.e. afterdetecting when a HF component appears on a LIN signal, the LIN networkis adapted to remove rectification of the LIN signal on the LIN buscaused by the HF component. An average value of the LIN voltage level isfiltered and fed back to an associated amplifier loop, to dictate andclean the threshold that sets the level of transition between high andlow voltage levels.

Referring now to FIG. 4, a LIN network 400 adapted in accordance withone embodiment of the present invention is illustrated. The transmitpath comprises an input node 105 coupled to a shape generator 110, whichprovides a LIN signal shape proportional to Vbat is applied between Vbatand one port of amplifier 445.

The output of amplifier 445 is input to a base port of a FET 475, whoseemitter port is fed by the supply voltage. The source port is fed to aLIN node 115. The LIN node is operably coupled to a resistor 470 inseries with a diode 465 or a by-pass switch (S1) that is underoperational control of high frequency diction logic 415. The input ofthe diode 465 is also operably coupled to the high frequency detectionlogic 415.

The input of the diode 465 is also operably coupled to a low pass filter440 comprising a resistor-capacitor (R/C) network. The low pass filter440 is operably coupled to a second switch (S2) 450 that feeds thesecond input port of the amplifier 445. In this manner, the second inputport of amplifier 445 is either fed a filtered signal from the low passfilter 440, or a dictated by Vbat and a resistive bridge 460, 470.

A receive path comprises a receive comparator 120, the output of whichis input to a receive node (rxd) 130. One input of the receivecomparator 120 is provided with a battery voltage 125 arranged to be 50%of the supply voltage (Vbat). The second input of the receive amplifier120 is isolated from ground by a capacitor 420 and coupled to the LINbus 115 via a resistor 425.

The LIN bus 115 is also operably coupled to a FET 490 via a second diode480. The emitter port of the FET 490 feeds a source port of FET 495,whose base port is operably coupled to a base port and a source port ofFET 498.

In the circuit configuration illustrated in FIG. 4, a closed looparrangement feeds back the average value of the LIN signal on the LINbus 115 through a low pass filter, as soon as a high frequency (HF)signal is detected in HF detector 415 on the LIN signal.

In operation, in response to the HF detector 415 detecting a highfrequency component on the LIN signal, the HF detector 415 outputs aswitch control signal to close switch S1 and set switch S2 450 to theleft, i.e. incorporating the low-pass filter 440. In this manner, thediode 465 is by-passed, thereby removing any signal rectification beingcommunicated on the LIN bus. Furthermore, the average value of the LINsignal is fed back (in a closed loop manner), and passed through thelow-pass (resistance-capacitor (R-C) filter to the receiver comparator120.

With the circuit configuration in FIG. 4 set up in this manner, thesignal provided to the receiver comparator 120, i.e. after passingthrough the R-C low-pass filter, is the average value of the LIN signalwith the HF component signal substantially removed. Thus, the averagevalue of the LIN signal at receive node 130 has almost no jitter, asshown later with respect to FIG. 8. Thus, the signals being compared atthe receiver comparator 120, particularly with regard to voltagetransitions being reflected on the rxd node, are substantiallyco-incident and therefore more accurate.

Furthermore, in operation and in response to the HF detector 415 notdetecting a high frequency component on the LIN signal 115, the HFdetector 415 outputs a switch control signal to open switch S1 and setswitch S2 450 to the right. In this manner, the LIN signal is thenpassed through the diode 465 and switch S2 couples the voltage valueprovided by the R4 bridge 460, 470, i.e. feeding back the LIN voltagevalue, to the second input port of amplifier 445.

Thus, the operation of the circuit comprises the steps of:

-   -   (i) detecting an HF signal;    -   (ii) changing an impedance on the bus to avoid rectification. In        one embodiment of the present invention, the impedance change is        implemented by-passing the first diode S1 465; and    -   (iii) feeding back the disturbed average value to the feedback        loop, incorporating the low-pass filter to minimise the effect        on determining a signal transition in receiver comparator 120.

In one embodiment of the present invention, it is envisaged that thefunction of both the first switch and active device 465, e.g. a diode,may be provided by a single PMOSFET.

Alternatively, it is envisaged that active device 465 may be implementedas a parasitic PNP transistor with a P collector connected to ground. Insuch an arrangement, the transistor may be configured to take, say, 10%of the bridge current 460, 470. With such a configuration, it may bedifficult to obtain sufficient accuracy due to the parasitic PNP. Thus,it is envisaged that a second resistive bridge may be used to feed backthe LIN information in normal mode.

In this manner, embodiments of the present invention provide advantagesover the prior art, as the prior art fails to address HF perturbationson the LIN bus 115.

Referring now to FIG. 5, a high frequency detector circuit 415 isillustrated. A capacitor C 545 is arranged to only pass a HF componentof the input signal, i.e. the signal on the LIN bus 115. A resistor R550 isolates Vgs(Mp2) from Vgs(Mp1). The HF detector is supplied by a DC5V power supply 555. In one embodiment of the present invention, this isarranged as a floating supply due to the circuit being attached (or atleast referenced) to Vbat 435.

The HF detector circuit 415 comprises a first loop, wherein the loopcomprises MOSFET transistor MP1 505 and MOSFET transistor MP3 510biasing the MOSFET transistor MP1 505 with I_(ref) 515. In this manner,the Vgs of MP1 505 has a DC value. Thus, when there is no HF componenton the input signal 520:Vgs(Mp1)=Vgs(Mp2).

Thus, MOSFET transistor MP2 520 is biased with a combination of I_(ref)525+I_(th) 530. In this manner, the gate port of MOSFET transistor Mn1535 is low and the logic output is low. Thus, the output 540 from the HFdetector 415 is low, signifying no HF component as being detected.

When a HF component is detected on the input signal 520, the negativepart of the HF sinusoidal signal component turns on the MOSFET Mp2 520,as soon as I(Mp2) is higher than I_(ref) 525+I_(th) 530. Hence, in thismanner, I_(th) 530 is used to adjust the threshold of the HF detection.Thus, the larger the threshold current level of I_(th) 530, the higheris the HF threshold before the HF detector circuit switches its outputcontrol signal 540 (to S1 and S2 of FIG. 4) to a HF mode of operation.MOSFET transistor Mn1 535 and capacitor C2 560 perform a function of apeak detector, arranged to keep a maximum value of the source of Mn1 535across C2 560.

Referring now to FIG. 6, and to highlight the benefits provided byembodiments of the present invention, let us consider the improvement inthe LIN circuit signals. FIG. 6 illustrates a Direct Power Injection(DPI) test circuit 600. A signal generator 655 generates a sinusoidalvoltage, say a maximum of 80V peak-to-peak, and together with a 50 ohmresistor 650 represents a model of a 50 ohms output generator. Theoutput of the generator 655 is coupled with the LIN signal through a 4.7nF capacitor 645.

The circuit being tested 400 represents the LIN module in the vehicle.The Vbat 305, the diode 310 and the resistor 315 arrange to pull-up ofthe voltage value on the LIN communication bus. The second diode 480 andcurrent source 490, 495 represent the by-pass switch function of the LINdriver, as described previously with respect to FIG. 4.

To decrease the parasitic effects of a HF component on the LINcommunication bus, a capacitor 635 is connected between the LINcommunication bus and ground. Due to the coupling capacitor 645, a HFsignal is superimposed on the low frequency (say of the order of 10 KHz)LIN signal.

Referring now to FIG. 7, a waveform 700 illustrates the problems causedby a HF component 710 on the prior art LIN communication bus. Inparticular, FIG. 7 shows the effect of both rectification due to bothdiodes 310 and 790. The average value of the sinusoidal voltage ishighlighted as dotted line 705. Due to rectification of diode D1 310,the sinusoidal HF component 710, which comprises a low frequency LINsignal and a high frequency component that have been rectified, isshifted over Vbat 305 when a (clean) LIN signal 730 would be deemed at ahigh level. Due to rectification of diode D2 790 the sinusoidal HFcomponent 710 is also notably shifted below ‘ground’ when the LIN signalis at low DC level.

Due to this shifted DC value, in response to a slow transition, theaverage value of sinusoidal voltage (705) no longer follows the LINsignal closely enough. Effectively, the LIN receiver compares the LINaverage value as it crosses the 50% threshold of Vbat 720. Thus, due tothe signal rectification, the input to the receiver comparator 120 isshifted 740. This results in a failure of the LIN receiver to output asignal transition within the stipulated mask 735 of +/−7 μsec.

Referring now to FIG. 8, a waveform 800 illustrates the performanceimprovement provided by embodiments of the present invention. The sameHF component 805 is shown on the average value of the LIN signal 815.However, in this case FIG. 8 shows the improvement in reducing thejitter on rxd output. In this case, the diode (diode 465 of FIG. 4) hasbeen by-passed, leaving the output stage only coupled to diode D2 490.As there is no longer a diode located between the LIN communication busand Vbat 435, there is no rectification of the LIN signal. The low passfilter 440 therefore takes the average value of sinusoidal voltage onthe LIN communication bus through the bridge resistor network 820. Thelow pass filter voltage 825 is fed back to amplifier 445, which thendrives the current source 530 and pulls down the current on the LIN busthrough the diode D2 490. The low pass filter voltage 825 is forced bythe closed loop nature of the circuit to be the same as the referencesignal 830 on amplifier 445. Due to this closed loop effect, the averagevalue 815 of the sinusoidal voltage 805 of the HF component is matchedwith the desired LIN signal value without any HF component 830. Hence,the jitter 840 on rxd is minimised.

Referring now to FIG. 9, a flowchart 900 illustrates one embodiment ofthe present invention with regard to operating a LIN network. Theprocess commences with the LIN network being powered on in step 905. Atleast one LIN signal is then transmitted on the single LIN communicationbus, as in step 910. A determination is then made as to whether the LINtransmission includes a high frequency component, as shown in step 915.If it is determined that the LIN transmission does not include a highfrequency component in step 915, the process continuously loops to step910.

However, if it is determined that the LIN transmission includes a highfrequency component in step 915, an active device, such as a diode,located between the LIN transmit driver and the LIN bus, is by-passed instep 920. Furthermore, in one embodiment of the present invention, anaverage value of the LIN signal is passed through a low-pass filterbefore being applied to the receiver comparator, as shown in step 925.In this manner, the LIN transmission has now had the effects of the highfrequency component removed from it, as shown in step 930. The processloops back to step 915 until a high frequency component is no longerdetected.

It will be understood that the improved LIN network and method ofoperation therefor, as described above, aims to provide one or more ofthe following advantages:

-   -   (i) A LIN driver can be designed to comply with the LIN        specification even though HF components may interfere with the        LIN communication bus;    -   (ii) The impedance on the LIN bus can be re-arranged to ensure        there is no rectification when HF perturbation is detected.    -   (iii) Jitter on the receiver path is significantly reduced.

In particular, it is envisaged that the aforementioned inventive conceptcan be applied by a semiconductor manufacturer to any singlecommunication line circuit. It is further envisaged that, for example, asemiconductor manufacturer may employ the inventive concept in a designof a stand-alone device, such as a LIN driver, or application-specificintegrated circuit (ASIC) and/or any other sub-system element.

It will be appreciated that any suitable distribution of functionalitybetween different functional units may be used without detracting fromthe inventive concept herein described. Hence, references to specificfunctional devices or elements are only to be seen as references tosuitable means for providing the described functionality, rather thanindicative of a strict logical or physical structure or organization.

Aspects of the invention may be implemented in any suitable formincluding hardware, software, firmware or any combination of these. Theelements and components of an embodiment of the invention may bephysically, functionally and logically implemented in any suitable way.Indeed, the functionality may be implemented in a single unit or IC, ina plurality of units or ICs or as part of other functional units.

In particular, it is envisaged that the aforementioned inventive conceptcan be applied by a semiconductor manufacturer to any integrated circuitcapable of operating in a single communication bus. It is furtherenvisaged that, for example, a semiconductor manufacturer may employ theinventive concept in a design of a stand-alone device orapplication-specific integrated circuit (ASIC) and/or any othersub-system element.

Although the present invention has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Rather, the scope of the present invention is limitedonly by the accompanying claims. Additionally, although a feature mayappear to be described in connection with particular embodiments, oneskilled in the art would recognize that various features of thedescribed embodiments may be combined in accordance with the invention.In the claims, the term ‘comprising’ does not exclude the presence ofother elements or steps.

Furthermore, although individual features may be included in differentclaims, these may possibly be advantageously combined, and the inclusionin different claims does not imply that a combination of features is notfeasible and/or advantageous. Also, the inclusion of a feature in onecategory of claims does not imply a limitation to this category, butrather indicates that the feature is equally applicable to other claimcategories, as appropriate.

Furthermore, the order of features in the claims does not imply anyspecific order in which the features must be performed and in particularthe order of individual steps in a method claim does not imply that thesteps must be performed in this order. Rather, the steps may beperformed in any suitable order. In addition, singular references do notexclude a plurality. Thus, references to “a”, “an”, “first”, “second”etc. do not preclude a plurality.

Thus, an improved LIN network and method of operation therefor have beendescribed, wherein the aforementioned disadvantages with prior artarrangements have been substantially alleviated.

The invention claimed is:
 1. A linear interconnect networking (LIN)network comprising: a transmit driver and a receive comparator forcommunicating on a single communication bus, wherein the transmit driveris operably coupled to a high frequency detector to detect a highfrequency component on a low frequency LIN signal and in response to thedetection of the high frequency the LIN network is arranged to performone or both of the following: route an average of the low frequency LINsignal having the high frequency component through a low pass filter;and bypass the low frequency LIN signal having the high frequencycomponent signal from being passed through an active device operablycoupled between the transmit driver and the single communication bus;and a first switch arranged in parallel to the active device andoperably coupled to the high frequency detector such that the firstswitch is switched to a closed position in a high frequency loop tobypass the active device when the high frequency component is detected.2. The LIN network of claim 1 wherein the active device is a diode. 3.The LIN network of claim 1, wherein an output of the high frequencydetector configures the LIN network to bypass the active device therebyremoving a rectification effect on the low frequency LIN signal causedby the active device due to the high frequency component.
 4. The LINnetwork of claim 1 further characterised in that the transmit driver isconfigured to operate in one of at least two modes utilising one of atleast two loops.
 5. The LIN network of claim 4 wherein one of the atleast two loops is a high frequency mode loop that is selected inresponse to the detection of the high frequency component on the lowfrequency LIN signal.
 6. The LIN network of claim 4 wherein the the oneof the at least two loops incorporates the low pass filter when the highfrequency component is detected.
 7. The LIN network of claim 1 wherein afunction of both the first switch and the active device is provided by asingle PMOSFET.
 8. The LIN network of claim 1, a receiver node thatreceives a fed back average of the low frequency LIN signal and comparesthe fed back average of the low frequency LIN signal with a thresholdvoltage” to —The LIN network of claim 1, comprising a receiver node thatreceives a fed back average of the low frequency LIN signal and comparesthe fed back average of the low frequency LIN signal with a thresholdvoltage.
 9. An integrated circuit for use in a linear interconnectnetworking (LIN) network comprising: a transmit driver and a receivecomparator for communicating on a single communication bus, the transmitdriver operably coupled to a high frequency detector to detect a highfrequency component on a low frequency LIN signal, and in response tothe detection of the high frequency component the integrated circuit isarranged to perform one or both of the following: route an average ofthe low frequency LIN signal having the high frequency componet througha low pass filter; and bypass the low frequency LIN signal having thehigh frequency component signal from being passed through an activedevice operably coupled between the transmit driver and the singlecommunication bus; and a first switch arranged in parallel to the activedevice and operably coupled to the high frequency detector such that thefirst switch is switched to a closed position in a high frequency loopto bypass the active device when the high frequency component isdetected.
 10. The integrated circuit of claim 9 wherein the activedevice is a diode.
 11. The integrated circuit of claim 9 wherein anoutput of the high frequency detector configures the integrated circuitto bypass the active device thereby removing a rectification effect onthe LIN low frequency signal caused by the active device due to the highfrequency component.
 12. The integrated circuit of claim 9, wherein thetransmit driver is configured to operate in one of at least two modesutilising one of at least two loops.
 13. The integrated circuit of claim12 wherein the one of the at least two loops is a high frequency modeloop that is selected in response to the detection of the high frequencycomponent on the low frequency LIN signal.
 14. The integrated circuit ofclaim 12 wherein the one of the at least two loops incorporates the lowpass filter when the high frequency component is detected.
 15. Anintegrated circuit for use in a linear interconnect networking (LIN)network comprising: a transmit driver and a receive comparator forcommunicating on a single communication bus, the transmit driveroperably coupled to a high frequency detector to detect a high frequencycomponent on a low frequency LIN signal, and in response to thedetection of the high frequency component the integrated circuit isarranged to perform one or both of the following; route an average ofthe low frequency LIN signal having the high frequency component througha low pass filter; and bypass the low frequency LIN signal having thehigh frequency component signal from being passed through an activedevice operably coupled between the transmit driver and the singlecommunication bus; and a receiver node that receives a fed back averageof the low frequency LIN signal and compares the fed back average of thelow frequency LIN signal with a threshold voltage.
 16. A method ofcommunication on a linear interconnect networking (LIN) networkcormprising a transmit driver operably coupled to a single communicationbus via an active device, the method comprising: communicating a lowfrequency LIN signal having a high frequency component on a singlecommunication bus: detecting the high frequency component on the lowfrequency LIN signal; in response to detecting, performing one or bothof the following: routing an average of the low frequency LIN signalhaving the high frequency component through a low pass filter; andbypassing the low frequency LIN signal having the high frequencycomponent signal from passing through the active device; switching afirst switch to a closed position in a high frequency loop when the highfrequency component is detected, wherein the first switch is arranged inparallel to the active device and operably coupled to the high frequencydetector; and bypassing the active device in response to the firstswitch being switched to the closed position.
 17. The method of claim 16further comprising: configuring the LIN network to bypass the activedevice to remove a rectification effect caused by the active device. 18.The method of claim 16 further comprising: routing the low frequency LINsignal having the high frequency component through a high frequency modeloop selected in response to detecting the high frequency component.